package com.t20;

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;

/**
 * Created by xuyiwei on 2018/9/15.
 */
public class TableCreator {
    public static void main(String[] args) throws Exception {
        if(args.length < 1) {
            System.out.println("arguments: annotated classes");
            System.exit(0);
        }
        for(String className : args) {
            Class<?> cl = Class.forName(className);
            DBTable dbTable = cl.getAnnotation(DBTable.class);
            if(dbTable == null) {
                System.out.println(  "No DBTable annotations in class " + className);
                continue;
            }
            String tableName = dbTable.name();
            if(tableName.length() < 1)   tableName = cl.getName().toUpperCase();
            List<String> columnDefs = new ArrayList<String>();
            for(Field field : cl.getDeclaredFields()) {
                String columnName = null;
                Annotation[] anns = field.getDeclaredAnnotations();
                if(anns.length < 1)  continue; // Not a db table column
                if(anns[0] instanceof SQLInteger) {
                    SQLInteger sInt = (SQLInteger) anns[0];
                    if(sInt.name().length() < 1)  columnName = field.getName().toUpperCase();
                    else  columnName = sInt.name();
                    columnDefs.add(columnName + " INT" + getConstraints(sInt.constraints()));
                }
                if(anns[0] instanceof SQLString) {
                    SQLString sString = (SQLString) anns[0];
                    if(sString.name().length() < 1)  columnName = field.getName().toUpperCase();
                    else columnName = sString.name();
                    columnDefs.add(columnName + " VARCHAR(" + sString.value() + ")" + getConstraints(sString.constraints()));
                }
                StringBuilder createCommand = new StringBuilder( "CREATE TABLE " + tableName + "(");
                for(String columnDef : columnDefs) createCommand.append("\n    " + columnDef + ",");
                 String tableCreate = createCommand.substring(  0, createCommand.length() - 1) + ");";
                System.out.println("Table Creation SQL for " +  className + " is :\n" + tableCreate);
            }
        }
    }
    private static String getConstraints(Constraints con) {
        String constraints = "";
        if(!con.allowNull()) constraints += " NOT NULL";
        if(con.primaryKey()) constraints += " PRIMARY KEY";
        if(con.unique()) constraints += " UNIQUE";
        return constraints;
    }
}
